Electromagnetic resonance coupler

ABSTRACT

An electromagnetic resonance coupler includes a transmission resonator provided on the transmission substrate and having a shape obtained by opening a loop shape including an inwardly recessed portion in part to make a transmission resonator slit, transmission wiring connected to the transmission resonator, a reception substrate, a reception resonator provided on the reception substrate and having the same size and shape as the transmission resonator, and reception wiring connected to the reception resonator. The transmission and reception resonators are symmetric with respect to a point and face each other so that their contours match. In the transmission resonator, at least part of wiring constituting the recessed portion is close to wiring other than the at least part of wiring at a distance less than or equal to four times the wiring width of the transmission resonator.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a continuation application of PCT International Application No.PCT/JP2012/003055 filed on May 10, 2012, designating the United Statesof America, which is based on and claims priority of Japanese PatentApplication No. 2011-105963 filed on May 11, 2011. The entiredisclosures of the above-identified applications, including thespecifications, drawings and claims are incorporated herein by referencein their entirety.

FIELD

One or more exemplary embodiments disclosed herein relate generally toelectromagnetic resonance couplers for use in non-contact powertransmission apparatuses, non-contact signal transmission apparatuses,and signal isolators.

BACKGROUND

A non-contact transmission apparatus is known in which power or signalsare transmitted among electrical apparatuses without requiring directconnection of the electrical apparatuses through wiring. For example,Patent Literature 1 discloses an electronic circuit element called a“digital isolator.”

This technology enables isolation to be established between the groundof a logic signal and the ground of an RF signal. For example,non-contact transmission technology such as described above is used in agate driving element such as a semiconductor switching element for powerelectronics, because the source potential of the semiconductor switchingelement varies based on a high voltage and thus it is necessary toinsulate a direct-current component between the interior of the gatedriving element and the power semiconductor switching element.

In transmission and reception of signals between a high-frequencysemiconductor chip and an external device, if the transmission line isconfigured using wire bonding, uncertain parasitic capacitance orinductance that influences the characteristics of high-frequency signalswill occur. The non-contact transmission technology as described aboveis also used in such a case.

As the non-contact transmission technology, electromagnetic resonancecouplers (also called “electromagnetic field resonance couplers”) thatuse the coupling of two electric wiring resonators as disclosed inPatent Literature 2 and Non-Patent Literature 1 have been gatheringgreat attention in recent years. A feature of the electromagneticresonance couplers is that highly efficient and long-range signaltransmission is possible.

CITATION LIST Patent Literature

-   [Patent Literature 1] Description of U.S. Pat. No. 7,692,444-   [Patent Literature 2] Japanese Unexamined Patent Application    Publication No. 2008-067012

Non Patent Literature

-   [Non-Patent Literature 1] Andre Kurs, et al., “Wireless Power    Transfer via Strongly Coupled Magnetic Resonances,” Science Express,    Vol. 317, No. 5834, pp. 83-86 (2007)

SUMMARY Technical Problem

It is an issue for the above-described electromagnetic resonancecouplers to reduce the apparatus size without increasing the frequencyof a high-frequency signal to be transmitted (operating frequency).

One non-limiting and exemplary embodiment provides an electromagneticresonance coupler that can be reduced in size without increasing theoperating frequency.

Solution to Problem

In one general aspect, the techniques disclosed here feature anelectromagnetic resonance coupler for transmitting a signal betweenfirst resonant wiring and second resonant wiring without contact. Theelectromagnetic resonance coupler includes a first substrate, and asecond substrate facing the first substrate, wherein the first resonantwiring and first input/output wiring are provided on the firstsubstrate, the first resonant wiring having a loop shape that includesan inwardly recessed portion and an opening, and the first input/outputwiring being connected to a first connection portion in the firstresonant wiring, the second resonant wiring and second input/outputwiring are provided on the second substrate, the second resonant wiringhaving the same wiring width and the same shape as the first resonantwiring, and the second input/output wiring being connected to a secondconnection portion in the second resonant wiring, when viewed in adirection perpendicular to a main face of the first substrate, the firstresonant wiring and the second resonant wiring are symmetric withrespect to a point, and contours of the first resonant wiring and thesecond resonant wiring match, a distance between the first resonantwiring and the second resonant wiring in a direction perpendicular tothe main face of the first substrate is less than or equal to one half awavelength of the signal, and in the first resonant wiring, at leastpart of wiring that constitutes the recessed portion is close to wiringother than the at least part of wiring that constitutes the recessedportion at a distance that is less than or equal to four times thewiring width of the first resonant wiring.

These general and specific aspects may be implemented using a system, amethod, an integrated circuit, a computer program, or acomputer-readable recording medium such as a CD-ROM, or any combinationof systems, methods, integrated circuits, computer programs, orcomputer-readable recording media.

Additional benefits and advantages of the disclosed embodiments will beapparent from the Specification and Drawings. The benefits and/oradvantages may be individually obtained by the various embodiments andfeatures of the Specification and Drawings, which need not all beprovided in order to obtain one or more of such benefits and/oradvantages.

Advantageous Effects

With the electromagnetic resonance couplers according to one or moreexemplary embodiments, it is possible to easily reduce size withoutincreasing operating frequency.

BRIEF DESCRIPTION OF DRAWINGS

These and other advantages and features will become apparent from thefollowing description thereof taken in conjunction with the accompanyingDrawings, by way of non-limiting examples of embodiments disclosedherein.

FIG. 1 is a schematic diagram of a conventional open-ringelectromagnetic resonance coupler.

FIG. 2 shows a transmission characteristic of the conventional open-ringelectromagnetic resonance coupler.

FIG. 3 is an oblique (perspective) view of an electromagnetic resonancecoupler according to Embodiment 1.

FIG. 4 is a cross-sectional view of the electromagnetic resonancecoupler according to Embodiment 1.

FIG. 5 is a top view of a transmission substrate according to Embodiment1.

FIG. 6 is a top view of a transmission resonator according to Embodiment1.

FIG. 7 is a top view illustrating a variation on the transmissionresonator according to Embodiment 1.

FIG. 8 shows a transmission characteristic of the electromagneticresonance coupler according to Embodiment 1.

FIG. 9 is a top view illustrating another variation on the transmissionresonator according to Embodiment 1.

FIG. 10 illustrates yet another variation on the transmission resonatoraccording to Embodiment 1.

FIG. 11 is an oblique (perspective) view of an electromagnetic resonancecoupler according to Embodiment 2.

FIG. 12 is a top view of a transmission substrate according toEmbodiment 2.

FIG. 13 shows a transmission characteristic of the electromagneticresonance coupler according to Embodiment 2.

FIG. 14 shows a signal transmission characteristic of theelectromagnetic resonance coupler according to Embodiment 2 when thelength of the outermost wiring has been changed.

FIG. 15 is a top view illustrating a variation on the transmissionresonator according to Embodiment 2.

FIG. 16 is a top view illustrating another variation on the transmissionresonator according to Embodiment 2.

DESCRIPTION OF EMBODIMENTS

(Underlying Knowledge Forming Basis of the Present Disclosure)

In relation to the electromagnetic resonance coupler disclosed in theBackground section, the inventors have found the following problem.

As described in the Background section, electromagnetic resonancecouplers that enable highly efficient and long-range signal transmissionare known as an example of the non-contact transmission technology.

Among these electromagnetic resonance couplers, an open-ringelectromagnetic resonance coupler as illustrated in FIG. 1 exhibits anexcellent transmission characteristic although its structure is simple.

FIG. 2 shows a transmission characteristic of a conventional open-ringelectromagnetic resonance coupler having the structure in FIG. 1.

In FIG. 2, S21 denotes an insertion loss with the open-ringelectromagnetic resonance coupler and indicates that electric signals ator near the frequency of 15 GHz can be efficiently transmitted with aninsertion loss of approximately 1 dB.

The frequency of signals that the open-ring electromagnetic resonancecoupler can transmit (operating frequency) is, to be precise, determinedby the inductance and capacitance of ring-shaped resonant wiring in theelectromagnetic resonance coupler. However, the operating frequency canbe approximately obtained as follows (Formula 1) from the effective areaof the ring-shaped wiring and the dielectric constant of a substrate onwhich the ring-shaped wiring is formed.

$\begin{matrix}{{fr} = {\frac{1}{2\pi \sqrt{LC}} \approx \frac{C}{2\pi \; a\sqrt{ɛ_{r}}}}} & \left\lbrack {{Formula}\mspace{14mu} 1} \right\rbrack\end{matrix}$

In Formula 1, c denotes the light velocity and ∈_(r) denotes therelative dielectric constant of the substrate (dielectric). Also, adenotes the effective area of the ring-shaped wiring, which isapproximately the diameter of the ring.

For example, the operating frequency band of an open-ringelectromagnetic resonance coupler that has a thickness of 200 μm and isformed on a sapphire substrate having a diameter of 1 mm as illustratedin FIG. 1 is at or near 15 GHz. It is found from Formula 1 that if thediameter of the open-ring electromagnetic resonance coupler is doubled,the operating frequency is reduced to one half, that is, the 7.5-GHzfrequency band.

When a power transmission apparatus is configured using an open-ringelectromagnetic resonance coupler, the open-ring electromagneticresonance coupler is integrated together with, for example, atransmission circuit element and a reception circuit element for use inpower and signal transmission.

Here, the transmission circuit element and the reception circuit elementare very small, on the order of several micrometers, whereas theopen-ring electromagnetic resonance coupler is large, on the order ofseveral millimeters, as mentioned above.

As can be seen from Formula 1 above, it is possible to reduce the sizeof the open-ring electromagnetic resonance coupler by increasing theoperating frequency. However, as the operating frequency increases, theopen-ring electromagnetic resonance coupler tends to be more influencedby its uncertain parasitic capacitance and inductance, and expensivetransmission and reception circuit elements that are compatible withhigh frequencies are necessary for proper operation.

Thus, the challenge is to realize an electromagnetic resonance couplerthat can be reduced in size without increasing the operating frequency.

According to an exemplary embodiment disclosed herein, theelectromagnetic resonance coupler is an electromagnetic resonancecoupler for transmitting a signal between first resonant wiring andsecond resonant wiring without contact. The electromagnetic resonancecoupler includes a first substrate, and a second substrate facing thefirst substrate, wherein the first resonant wiring and firstinput/output wiring are provided on the first substrate, the firstresonant wiring having a loop shape that includes an inwardly recessedportion and an opening, and the first input/output wiring beingconnected to a first connection portion in the first resonant wiring,the second resonant wiring and second input/output wiring are providedon the second substrate, the second resonant wiring having the samewiring width and the same shape as the first resonant wiring, and thesecond input/output wiring being connected to a second connectionportion in the second resonant wiring, when viewed in a directionperpendicular to a main face of the first substrate, the first resonantwiring and the second resonant wiring are symmetric with respect to apoint, and contours of the first resonant wiring and the second resonantwiring match, a distance between the first resonant wiring and thesecond resonant wiring in a direction perpendicular to the main face ofthe first substrate is less than or equal to one half a wavelength ofthe signal, and in the first resonant wiring, at least part of wiringthat constitutes the recessed portion is close to wiring other than theat least part of wiring that constitutes the recessed portion at adistance that is less than or equal to four times the wiring width ofthe first resonant wiring.

With this, it is possible to increase the inductance components of theresonant wirings by providing the resonant wirings close to each other.Accordingly, the operating frequency can be reduced in accordance withFormula 1. That is, it is possible to reduce the size of theelectromagnetic resonance coupler.

For example, the opening may be provided in at least part of wiring thatconstitutes the recessed portion.

With this, it is possible to increase the capacitance components of theresonant wirings by bringing the opening of each resonant wiring closeto the other resonant wiring. Accordingly, the operating frequency canbe reduced in accordance with Formula 1. That is, it is possible toreduce the size of the electromagnetic resonance coupler.

For example, the first resonant wiring may have a shape that includesfive or more bent portions.

With this, it is possible to reduce the areas occupied by the resonantwirings on the substrates. That is, the size of the electromagneticresonance coupler can be reduced. There is also an effect of increasedinductance components of the resonant wirings due to the densely packedwirings. Accordingly, it is possible to reduce the size of theelectromagnetic resonance coupler.

For example, a contour of the first resonant wiring, excluding wiringthat constitutes the recessed portion, may be rectangular.

With this, it is possible to reduced the areas occupied by the resonantwirings on the substrates. That is, the size of the electromagneticresonance coupler can be reduced.

For example, the first resonant wiring may have a symmetrical shape.

Thus forming the resonant wirings in a symmetrical shape enables signaltransmission in a wide frequency band.

For example, ground wiring that represents a reference potential of thesignal may be provided on a face of the first substrate on which thefirst resonant wiring is not provided or a face of the second substrateon which the second resonant wiring is not provided.

The electromagnetic resonance coupler may further include a capsubstrate facing the second substrate, wherein ground wiring thatrepresents a reference potential of the signal may be provided on a faceof the cap substrate opposite the second substrate.

For example, ground wiring that represents a reference potential of thesignal may be provided in a periphery of the first resonant wiring andthe first input/output wiring on the first substrate or in a peripheryof the second resonant wiring and the second input/output wiring on thesecond substrate.

The electromagnetic resonance coupler may further include a capsubstrate facing the second substrate, wherein first ground wiring thatrepresents a reference potential of the signal may be provided on a faceof the cap substrate opposite the second substrate, second ground wiringthat represents the reference potential of the signal may be provided ina periphery of the second resonant wiring and the second input/outputwiring on the second substrate, and the first ground wiring and thesecond ground wiring may be connected to each other through a via hole.

Thus appropriately providing the ground wirings in the electromagneticresonance coupler enhances confinement of the electromagnetic field of ahigh-frequency signal to be transmitted. It is thus possible to transmitthe signal with high efficiency and to suppress unwanted radiation tothe outside.

For example, the first connection portion may be provided at a positionthat is away from one end of the first resonant wiring by a distancecorresponding to one fourth a wiring length of the first resonantwiring, and the second connection portion may be provided at a positionthat is away from one end of the second resonant wiring by a distancecorresponding to one fourth a wiring length of the second resonantwiring.

According to an exemplary embodiment disclosed herein, theelectromagnetic resonance coupler is an electromagnetic resonancecoupler for transmitting a signal between first resonant wiring andsecond resonant wiring without contact. The electromagnetic resonancecoupler includes a first substrate, and a second substrate facing thefirst substrate, wherein the first resonant wiring and firstinput/output wiring are provided on the first substrate, the firstresonant wiring having a loop shape of a predetermined wiring width, andthe first input/output wiring being connected to a first connectionportion in the first resonant wiring, the second resonant wiring andsecond input/output wiring are provided on the second substrate, thesecond resonant wiring having the same wiring width and the same shapeas the first resonant wiring, and the second input/output wiring beingconnected to a second connection portion in the second resonant wiring,when viewed in a direction perpendicular to a main face of the firstsubstrate, the first resonant wiring and the second resonant wiring aresymmetric with respect to a point, and contours of the first resonantwiring and the second resonant wiring match, a distance between thefirst resonant wiring and the second resonant wiring in the directionperpendicular to the main face of the first substrate is less than orequal to one half a wavelength of the signal, and a wiring length froman outer end of the first resonant wiring to the first connectionportion is longer than a wiring length from an inner end of the firstresonant wiring to the first connection portion and is less than orequal to one half a wiring length of wiring that is routed along anoutermost periphery of the first resonant wiring.

For example, the first resonant wiring may have a shape that includestwo or more bent portions in wiring that extends from the inner end ofthe first resonant wiring to the first connection portion, and two ormore bent portions in wiring that extends from the outer end of thefirst resonant wiring to the first connection portion.

With this, it is possible to reduce the areas occupied by the resonantwirings on the substrates. That is, the size of the electromagneticresonance coupler can be reduced.

For example, wiring that extends from the inner end of the firstresonant wiring to the first connection portion may include a portionthat is close to wiring that extends from the outer end of the firstresonant wiring to the first connection portion at a distance that isless than or equal to four times the predetermined wiring width.

With this, it is possible to increase the inductance components of theresonant wirings by bringing the resonant wirings close to each other.Accordingly, the operating frequency can be reduced in accordance withFormula 1. That is, it is possible to reduce the size of theelectromagnetic resonance coupler.

For example, a contour of the first resonant wiring may be rectangular.

With this, it is possible to reduce the areas occupied by the resonantwirings on the substrates. That is, the size of the electromagneticresonance coupler can be reduced.

For example, the first resonant wiring may have a symmetrical shape.

Thus forming the resonant wirings in a symmetrical shape enables signaltransmission in a wide frequency band.

For example, ground wiring that represents a reference potential of thesignal may be provided on a face of the first substrate on which thefirst resonant wiring is not provided or a face of the second substrateon which the second resonant wiring is not provided.

The electromagnetic resonance coupler may further include a capsubstrate superimposed above the second substrate, wherein ground wiringthat represents a reference potential of the signal may be provided on aface of the cap substrate opposite the second substrate.

For example, ground wiring that represents a reference potential of thesignal may be provided in a periphery of the first resonant wiring andthe first input/output wiring on the first substrate or in a peripheryof the second resonant wiring and the second input/output wiring on thesecond substrate.

The electromagnetic resonance coupler may further include a capsubstrate superimposed above the second substrate, wherein first groundwiring that represents a reference potential of the signal may beprovided on a face of the cap substrate opposite the second substrate,second ground wiring that represents the reference potential of thesignal may be provided in a periphery of the second resonant wiring andthe second input/output wiring on the second substrate, and the firstground wiring and the second ground wiring may be connected to eachother through a via hole.

Thus appropriately providing the ground wirings in the electromagneticresonance coupler enhances confinement of the electromagnetic field of ahigh-frequency signal to be transmitted. It is thus possible to transmitthe signal with high efficiency and to suppress unwanted radiation tothe outside.

These general and specific aspects may be implemented using a system, amethod, an integrated circuit, a computer program, or acomputer-readable recording medium such as a CD-ROM, or any combinationof systems, methods, integrated circuits, computer programs, orcomputer-readable recording media.

Hereinafter, certain exemplary embodiments are described in greaterdetail with reference to the accompanying drawings.

Each of the exemplary embodiments described below shows a general orspecific example. The numerical values, shapes, materials, structuralelements, the arrangement and connection of the structural elements,steps, the processing order of the steps etc. shown in the followingexemplary embodiments are mere examples, and therefore do not limit thescope of the appended claims and their equivalents. Therefore, among thestructural elements in the following exemplary embodiments, structuralelements not recited in any one of the independent claims are describedas arbitrary structural elements.

Embodiment 1

(Structure)

First, the structure of an electromagnetic resonance coupler accordingto Embodiment 1 will be described.

FIG. 3 is an oblique (perspective) view of the electromagnetic resonancecoupler according to Embodiment 1.

FIG. 4 is a cross-sectional view of the electromagnetic resonancecoupler in FIG. 3, taken along a broken line connecting A and A′ andalong a plane perpendicular to substrates.

An electromagnetic resonance coupler 10 includes a transmissionsubstrate 101 (first substrate), a reception substrate 102 (secondsubstrate) provided above the transmission substrate 101, and a capsubstrate 103 provided above the reception substrate 102. Thetransmission substrate 101, the reception substrate 102, and the capsubstrate 103 are dielectrics. In Embodiment 1, the material for thedielectrics is sapphire. Note that the dielectrics may be made ofanother material including a silicon semiconductor.

As illustrated in FIG. 4, a back face ground 112 is disposed on theunderside of the transmission substrate 101. The back face ground 112 isa metal conductor. The material for the back face ground 112 is, forexample, gold. The back face ground 112 is wiring that represents areference potential of a high-frequency signal to be transmitted in thetransmission substrate 101.

As illustrated in FIG. 4, transmission wiring 104 (first input/outputwiring) and a transmission resonator 105 (first resonant wiring) aredisposed on a top face of the transmission substrate 101. One end of thetransmission wiring 104 is electrically connected to the transmissionresonator 105 on a first connection portion of the transmissionresonator 105. The first connection portion is provided at a positionthat is away from one end of the transmission resonator 105 by adistance corresponding to one fourth the wiring length of thetransmission resonator 105. The transmission wiring 104 and thetransmission resonator 105 are configured by metal wiring. The materialfor the metal wiring is, for example, gold.

The transmission resonator 105 has a transmission resonator slit 106(opening). The details of the shape of the transmission resonator 105will be described later.

As illustrated in FIG. 3, a coplanar ground 113 is disposed apredetermined distance away from and in the periphery of thetransmission resonator 105 and the transmission wiring 104 on the topface of the transmission substrate 101. The coplanar ground 113 is ametal conductor. The material for the metal conductor is, for example,gold. The coplanar ground 113 is wiring that represents the referencepotential of a high-frequency signal to be transmitted in thetransmission substrate 101.

Note that the back face ground 112 and the coplanar ground 113 may beconnected to each other through a via hole. This improves the efficiencyof the electromagnetic resonance coupler 10 in transmitting ahigh-frequency signal.

In the transmission wiring 104, one end that is not connected to thetransmission resonator 105 is an input terminal 110. For the purpose ofconnecting an upstream circuit to the input terminal 110, the receptionsubstrate 102 is not disposed above the input terminal 110. That is, thereception substrate 102 is not formed above the input terminal 110. Theinput terminal 110 included in the transmission wiring 104 receivesinput of a high-frequency signal transmitted by the electromagneticresonance coupler 10.

As illustrated in FIG. 4, reception wiring 107 (second input/outputwiring) and a reception resonator 108 (second resonant wiring) aredisposed on a top face of the reception substrate 102. One end of thereception wiring 107 is electrically connected to the receptionresonator 108 on a second connection portion of the reception resonator108. The second connection portion is provided at a position that isaway from one end of the reception resonator 108 by a distancecorresponding to one fourth the wiring length of the reception resonator108. The reception wiring 107 and the reception resonator 108 areconfigured by metal wiring. The material for the metal wiring is, forexample, gold.

The reception resonator 108 has a reception resonator slit 109(opening). The shape of the reception resonator 108 will be describedlater.

As illustrated in FIG. 3, a coplanar ground 113 is disposed apredetermined distance away from and in the periphery of the receptionresonator 108 and the reception wiring 107 on the top face of thereception substrate 102. The coplanar ground 113 is a metal conductor.The material for the metal conductor is, for example, gold.

In the reception wiring 107, one end that is not connected to thereception resonator 108 is an output terminal 111. For the purpose ofconnecting a downstream circuit to the output terminal 111, the capsubstrate 103 is not disposed above the output terminal 111. That is,the cap substrate 103 is not formed above the output terminal 111. Theoutput terminal 111 included in the reception wiring 107 outputs asignal that is input to the electromagnetic resonance coupler 10.

A cap ground 114 is formed on a top face of the cap substrate 103 so asto cover the top face. The cap ground 114 is a metal conductor. Thematerial for the cap ground 114 is, for example, gold.

Note that the cap ground 114 is wiring that represents the referencepotential of a high-frequency signal to be transmitted in the receptionsubstrate 102.

The transmission resonator 105 and the reception resonator 108 has thesame shape of wiring and the same size. The transmission resonator 105and the reception resonator 108 face each other in a directionperpendicular to the transmission substrate 101 (the reception substrate102 or the cap substrate 103). More specifically, when viewed in adirection perpendicular to a main face of the transmission substrate 101(face of the transmission substrate 101 on which the transmissionresonator 105 and the transmission wiring 104 are provided), thetransmission substrate 101 and the reception substrate 102 aresuperimposed on each other so that the contours of the transmissionresonator 105 and the reception resonator 108 match.

Here, the contour of the transmission resonator 105 is defined asfollows. If it is assumed that the transmission resonator 105 has notransmission resonator slit 106 and is configured as closed wiringhaving a loop shape, the closed wiring of a loop shape has two contours:an inner (inside) contour that defines an area surrounded by the closedwiring of a loop shape; and an outer (outside) contour that defines theshape of the closed wiring of a loop shape together with the innercontour. Among these two contours, the contour of the transmissionresonator 105 means the outer contour. In other words, the inner contourand the outer contour define the wiring width of the transmissionresonator 105, and the outer contour defines the area occupied by thetransmission resonator 105.

The transmission resonator 105 and the reception resonator 108 aredisposed facing each other in the direction perpendicular to the mainface of the transmission substrate 101 so that they are symmetric withrespect to a point of intersection between the central axis of theshapes of wirings on the transmission resonator 105 and the receptionresonator 108 and an intermediate plane between the transmissionresonator 105 and the reception resonator 108.

The “intermediate plane” as used here refers to, among planes parallelto the transmission substrate 101, a plane that passes through anintermediate point (midpoint) of the distance between the transmissionresonator 105 and the reception resonator 108 in the directionperpendicular to the main face of the transmission substrate 101. Thatis, when viewed in the direction perpendicular to the main face of thetransmission substrate 101, the transmission substrate 101 and thereception substrate 102 are superimposed on each other so that theirshapes are symmetric with respect to a point.

FIG. 5 illustrates the shape of the metal wiring that is formed on thetop face of the transmission substrate 101 and includes the transmissionwiring 104 and the transmission resonator 105. Hereinafter, the shape ofthe transmission resonator 105 will be described. Note that since thereception resonator 108 has the same shape and size as the transmissionresonator 105 as mentioned above, a description thereof has beenomitted.

The transmission resonator 105 has a shape obtained by opening (cutting)the loop-shaped wiring at one place to make the transmission resonatorslit 106. That is, part of the transmission resonator 105 is opened bythe transmission resonator slit 106.

The above loop shape is a shape that includes two recessed portions thatare recessed inwardly of the loop shape. The term “inwardly” as usedhere means the center side (central side) of the loop shape when viewedin the direction perpendicular to the main face of the transmissionsubstrate 101. In other words, if it is assumed that the transmissionresonator 105 has no transmission resonator slit 106 and is configuredas closed wiring having a loop shape, the term “inwardly” as used hererefers to the side of an area enclosed by the closed wiring of the loopshape. In the transmission resonator 105, the transmission resonatorslit 106 is provided in wiring that constitutes one of the recessedportions.

If there is no transmission resonator slit 106, the transmissionresonator 105 of a loop shape has a line symmetrical shape with respectto a straight line that divides the transmission wiring 104 into twoequal parts in the wiring direction. The transmission resonator 105 alsohas a line symmetrical shape with respect to a straight line that passesthrough the center of the transmission resonator slit 106 and isperpendicular to the above straight line. If there is no transmissionresonator slit 106, the transmission resonator 105 of a loop shape has apoint symmetrical shape with respect to the central point of thetransmission resonator 105. That is, the shape of the transmissionresonator 105 is a symmetrical shape. In other words, the two recessedportions are provided so as to be symmetric with respect to a straightline that divides the transmission wiring 104 into two equal parts inthe wiring direction.

While the transmission resonator 105 in Embodiment 1 has a linesymmetrical shape, it may achieve similar functionality even if nothaving line symmetry. Note that the loop shape refers to a closed shapein which one wiring intersects with neither another wiring nor part ofits own wiring. One example is a ring shape. The details of the shape ofthe transmission resonator 105 will be described later.

As described above, the reception resonator 108 disposed facing thetransmission resonator 105 has the same shape as the transmissionresonator 105.

By in this way, disposing the two wirings, each having a loop shapeopened by a slit, a predetermined distance away from each other,electromagnetic resonance coupling is established between the twowirings having a loop shape (transmission resonator 105 and receptionresonator 108).

In order to establish strong electromagnetic resonance coupling betweenthe transmission resonator 105 and the reception resonator 108, thedistance between the transmission resonator 105 and the receptionresonator 108 in the direction perpendicular to the main face of thetransmission substrate 101 needs to be less than or equal toapproximately the wavelength of a high-frequency signal transmitted bythe electromagnetic resonance coupler 10.

In Embodiment 1, the transmission substrate 101 and the receptionsubstrate 102 are superimposed on each other so that the distancebetween the transmission resonator 105 and the reception resonator 108in the direction perpendicular to the main face of the transmissionsubstrate 101 is less than or equal to one half the wavelength of ahigh-frequency signal to be transmitted. Specifically, the receptionsubstrate 102 is formed to a thickness (length in the directionperpendicular to the main face of the reception substrate 102) that isless than or equal to one half the wavelength of a high-frequency signalto be transmitted.

Here, the wavelength of a high-frequency signal is a wavelength thattakes into consideration a velocity factor of the material for thewirings in which the signal is transmitted, and a velocity factor of thedielectric that intervenes between the transmission resonator 105 andthe reception resonator 108. In Embodiment 1, these velocity factors aredetermined by gold as the material for the wirings and sapphire as thebase material.

The above has been a description of the structure of the electromagneticresonance coupler 10 according to Embodiment 1.

Note that in the structure of FIG. 3, the transmission substrate 101 hasa coplanar line structure in which the coplanar ground 113 is providedin the periphery of the transmission wiring 104. Specifically, asillustrated in FIG. 3, the coplanar ground 113 is provided at a positionthat is a distance d4 away from the outer contours of the transmissionresonator 105 and the transmission wiring 104 (in the case of thetransmission resonator 105, the contour excluding the recessedportions). Alternatively, the transmission substrate 101 may have amicro-strip line structure or a grounded coplanar line structure.

In the structure of FIG. 3, the reception substrate 102 may have acoplanar line structure in which a coplanar ground is provided in theperiphery of the reception wiring 107. In this case, the coplanar groundformed in the periphery of the reception wiring 107 and the cap ground114 may be electrically connected to each other through a via hole 140as illustrated in FIG. 4. This improves the efficiency of theelectromagnetic resonance coupler 10 in transmitting a high-frequencysignal. Alternatively, the reception substrate 102 may have a groundedcoplanar line structure.

(Shape of Resonators)

Now, the shapes of the resonators of the electromagnetic resonancecoupler 10 according to Embodiment 1 will be described.

The electromagnetic resonance coupler 10 according to Embodiment 1 canreduce its operating frequency by changing the shapes of thetransmission resonator 105 and the reception resonator 108.

In general, the self-resonant frequency of a resonator (LC resonator) isdetermined based on the self-inductance (L) and self-capacitance (C) ofthe resonator as follows (Formula 2). That is, the self-resonantfrequency of the resonator decreases as the inductance component and thecapacitance component increase.

$\begin{matrix}{{fr} = \frac{1}{2\pi \sqrt{LC}}} & \left\lbrack {{Formula}\mspace{14mu} 2} \right\rbrack\end{matrix}$

In the case of an open-ring electromagnetic resonance coupler, theself-inductances of the resonators are determined based on wirings, andthe self-capacitances are determined based on cut slits formed in thewirings of the resonators.

Also, in the case of the open-ring electromagnetic resonance coupler,the inductance or capacitance components of the resonators can beincreased by concentrating the electromagnetic field between theresonators that are superimposed on each other. Specifically, forexample, the capacitance components of the resonators can be increasedby intensifying the electromagnetic field at the slits.

In the electromagnetic resonance coupler 10 according to Embodiment 1,the capacitance component of the transmission resonator 105 is increasedby densely packing the wirings in the periphery of the transmissionresonator slit 106 and thereby intensifying the electromagnetic field inthe periphery of the transmission resonator slit 106. This results in areduction in the operating frequency of the electromagnetic resonancecoupler 10.

In the electromagnetic resonance coupler 10 according to Embodiment 1,part of the wiring that forms the transmission resonator 105 is shapedto be close to the transmission resonator slit 106. That is, thecapacitance component of the transmission resonator 105 is increased bydensely packing the wiring in the periphery of the transmissionresonator slit 106 and thereby intensifying the electromagnetic field inthe periphery of the transmission resonator slit 106. This results in areduction in the operating frequency of the electromagnetic resonancecoupler 10.

The transmission resonator 105 illustrated in FIG. 5 is a closed circuitthat is formed of a single metal wire and that has an cutaway portion(opening) in part. Hereinafter, this cutaway portion is referred to asthe “transmission resonator slit 106”. The closed circuit does notnecessarily have to be formed of a single metal wire, and it means acircuit that is electrically connected. The “closed circuit” as usedhere carries similar meaning as forming a closed space (internal space1053 in FIG. 6) when viewed from above the transmission substrate 101.

A densely packed wiring lateral distance d1 in FIG. 5 is a distance inthe horizontal direction between the transmission resonator slit 106 anda portion that is close to the transmission resonator slit 106 in thetransmission resonator 105, when viewed in the direction perpendicularto the main face of the transmission substrate 101 (when viewed fromabove). Here, the “horizontal direction” refers to a horizontaldirection when viewed from above the transmission substrate 101 in astate in which the transmission resonator 105 is disposed above thetransmission wiring 104 as illustrated in FIG. 5. That is, thehorizontal direction is a direction perpendicular to the transmissionwiring 104.

In FIG. 5, the two recessed portions of the transmission resonator 105are respectively referred to as a first recessed portion (left-siderecessed portion in FIG. 5) and a second recessed portion (right-siderecessed portion in FIG. 5). The densely packed wiring lateral distanced1 specifically means a distance between wiring 120 b where thetransmission resonator slit 106 is provided, among wirings 120 a, 120 b,and 120 c that constitute the first recessed portion, and wiring 130 damong the wiring that constitutes the second recessed portion.

Here, the electromagnetic field of a high-frequency signal thatpropagates through wirings spreads and propagates in accordance with thewiring width. The degree of spread of the electromagnetic field isdetermined by the degree of confinement of the wirings, and it roughlyspreads to approximately four times the wiring width. That is, if it isdesired to intensity the electromagnetic field, it is preferable for thewirings to be close to each other in the range of approximately fourtimes the wiring width. Accordingly, the densely packed wiring lateraldistance d1 is a length that is in the range of four times the wiringwidth of the transmission resonator 105.

Also, in FIG. 5, distances in the vertical direction between metalwirings included in the transmission resonator 105, when viewed fromabove, are illustrated as “densely packed wiring longitudinal distancesd2 and d3.”

The densely packed wiring longitudinal distance d3 specifically means adistance between the wiring 12 a and the wiring 12 c among the wirings120 a, 120 b, and 120 c that constitute the first recessed portion. Thedensely packed wiring lateral distance d3 is a length that is in therange of four times the wiring width of the transmission resonator 105.

In summary, in the transmission resonator 105, at least some of thewirings 120 a, 120 b, and 120 c that constitute the recessed portion areclose to wiring other than the at least some of the wirings at adistance less than or equal to four times the wiring width. Also, inEmbodiment 1, the densely packed wiring longitudinal distances d2 and d3are equal because the transmission resonator 105 has a line symmetricalshape. Thus, a description of the densely packed wiring longitudinaldistance d2 has been omitted.

In this way, densely packing the wirings and concentrating theelectromagnetic field in the periphery of the transmission resonatorslit 106 is equivalent to increasing the self-capacitance component ofthe transmission resonator 105. Also, bringing the wirings in thetransmission resonator 105 close to each other and concentrating theelectromagnetic field is equivalent to increasing the self-inductancecomponent of the transmission resonator 105.

Accordingly, the operating frequency of the electromagnetic resonancecoupler 10 can be reduced by providing the recessed portions on thetransmission resonator 105.

In other words, the operating frequency is determined by the denselypacked wiring lateral distance d1, the densely packed wiringlongitudinal distances d2 and d3, and the width of the metal wiringconstituting the transmission resonator 105.

Furthermore, providing the recessed portions on the inner side of thetransmission resonator 105 (on the inner peripheral side of the loopshape) increases the wiring length of the transmission resonator 105 inthe same area on the substrate. The operating frequency is also reducedby increasing the wiring length in this way.

Next, the shape of the transmission resonator 105 will be describedfocusing on two parts: the recessed portions and the other portion.

FIG. 6 illustrates the shape of the transmission resonator 105, viewedfrom above.

The transmission resonator 105 includes first wiring 1051 and secondwiring 1052 that constitutes the recessed portions.

The wiring indicated by the solid line in FIG. 6 is the first wiring1051 formed of linear wires. The first wiring 1051 is wiring that doesnot constitute the recessed portions. In other words, the first wiring1051 is bracket-shaped wiring that defines the internal space 1053 ofthe transmission resonator 105.

The internal space 1053 is a square area enclosed by the single-dotbroken line in FIG. 6. Note that the shape of the first wiring 1051 isnot limited to that bracket shape. For example, the first wiring 1051may have an angled bracket shape or a round bracket shape. In this case,the internal space 1053 has a shape of a polygon or a circle (ellipse).

Note that the contour of the transmission resonator 105 excluding thewiring that constitutes the recessed portions is rectangular. Here, thecontour excluding the recessed portions means the outer contour of thetransmission resonator 105 in the case where the transmission resonator105 is configured without forming recessed portions, and it correspondsto a contour 1054 in FIG. 6.

The second wiring 1052 is wiring having a shape indicated by the dottedline in FIG. 6. The second wiring 1052 is wiring that constitutes therecessed portions formed in the internal space 1053 of the transmissionresonator 105, and is formed of linear wires. That is, when viewed fromabove, the recessed portions of the transmission resonator 105 arerecessed on the internal space 1053 side, i.e., on the inner side. Thesecond wiring 1052 includes the transmission resonator slit 106.

The distance d1 between the transmission resonator slit 106 and thesecond wiring 1052 is shorter than a distance d5 between thetransmission resonator slit 106 and the first wiring 1051. By formingthe transmission resonator slit 106 and the second wiring 1052 in theinternal space 1053 of the transmission resonator 105, the metal wiringincluded in the transmission resonator 105 can be formed in the vicinityof the transmission resonator slit 106.

That is, the transmission resonator 105 that includes the second wiring1052 can concentrate the electromagnetic field in the periphery of thetransmission resonator slit 106, more than in the case where thetransmission resonator is formed of only the first wiring 1051surrounding the internal space 1053. This results in a reduction in theelectromagnetic resonant frequency (operating frequency) of thetransmission resonator 105.

The transmission resonator slit 106 is provided in the vicinity of thecenter of an area (internal space 1053) that is surrounded by the wiringforming the transmission resonator 105. The transmission resonator 105has a shape in which the other part of the wiring forming thetransmission resonator 105 is brought close to two opposite wiring endsformed by cutting out the transmission resonator slit 106. Such a shapeof wiring in which the capacitance component is increased by bringingthe other part of the wiring close to the transmission resonator slit106 and the inductance component is increased by bringing the wirings ofthe transmission resonator 105 close to each other is the feature of thetransmission resonator 105.

Note that the transmission resonator 105 has a shape that includes 12bent portions, each surround by a circular dotted line in FIG. 6. Thatis, the transmission resonator 105 has a shape that includes five ormore bent portions. In the case where the transmission resonator 105excluding the wiring constituting the recessed portions has arectangular contour as illustrated in FIG. 6, the bent portions areright-angled bent portions on the transmission resonator 105.

Note that the second wiring 1052 (recessed portions) has a bracket shapein FIG. 6, it is not limited to this shape. For example, the secondwiring 1052 may have an angled bracket shape or a round bracket shape.

FIG. 7 shows an example of a transmission resonator in which recessedportions have an angled bracket shape. A transmission resonator 205 asillustrated in FIG. 7 can also increase its self-capacitance componentbecause a transmission resonator slit 206 is close to a bent portion 210c of the transmission resonator 205.

Note that the transmission resonator 205 illustrated in FIG. 7 has ashape that includes five bent portions 210 a to 210 e. That is, the bentportions do not always mean right-angled bent portions as illustrated inFIG. 6.

Hereinafter, a specific configuration (material and size) of theelectromagnetic resonance coupler 10 will be described.

The materials for the transmission substrate 101, the receptionsubstrate 102, and the cap substrate 103 are sapphire substrates havinga thickness of 200 μm.

The transmission wiring 104, the transmission resonator 105, thereception wiring 107, and the reception resonator 108 have a wiringwidth of 100 μm and are made of gold. The transmission resonator 105 andthe reception resonator 108 have dimensions of 1 mm by 1 mm (W1=L1=1mm), viewed from above the electromagnetic resonance coupler 10 (in thedirection perpendicular to the main face of the transmission substrate101).

The transmission resonator slit 106 has a width (S1) of 40 μm. The“width” as used here refers to a width in a direction perpendicular tothe wiring width and is denoted by S1 in FIG. 5.

The densely packed wiring lateral distance indicated by d1 in FIG. 5 is40 μm, and the densely packed wiring longitudinal distance indicated byd2 is 0.1 mm.

The coplanar ground 113 is formed at a position that is 140 μm(corresponding to d4 in FIG. 5) away from the contours of thetransmission resonator 105 and the transmission wiring 104 on thetransmission substrate 101.

(Transmission Characteristic)

Next, a signal transmission characteristic of the electromagneticresonance coupler 10 will be described.

A high-frequency signal that is input from the input terminal 110 passesthrough the transmission wiring 104 and reaches the transmissionresonator 105.

In the case where the two resonators (transmission resonator 105 andreception resonator 108) having the same self-resonant frequency arespaced from each other by a distance that allows electromagnetic fieldcoupling, the two resonators make electromagnetic resonance couplingthat triggers resonance at the resonant frequency.

Thus, when a high-frequency signal at the resonant frequency is input tothe transmission resonator 105, a high-frequency signal at the sameresonant frequency will occur in the reception resonator 108. Note thatthe resonant frequency of the electromagnetic resonance coupler 10 has acertain degree of bandwidth, and the electromagnetic resonance coupler10 can transmit high-frequency signals in this frequency band.

Thus, only high-frequency signals in the resonant frequency band aretransmitted to the reception resonator 108, and high-frequency signalsoutside the resonant frequency band are not transmitted to the receptionresonator 108.

A high-frequency signal transmitted to the reception resonator 108 isoutput to the output terminal 111 through the reception wiring 107connected to the reception resonator 108. Because the transmissionwiring 104 and the transmission resonator 105 are physically separatedfrom the reception wiring 107 and the reception resonator 108, thehigh-frequency signal is transmitted without contact.

In the electromagnetic resonance coupler 10 with the above-describedconfiguration according to Embodiment 1, the frequency of ahigh-frequency signals to be transmitted is 9.5 GHz. Now, thetransmission characteristic in this frequency band will be described.

FIG. 8 shows the transmission characteristic of the electromagneticresonance coupler 10 according to Embodiment 1.

A signal transmission rate S21 from the input terminal 110 to the outputterminal 111, and signal reflectance S11 at the input terminal 110 areshown in FIG. 8.

The signal transmission rate S21 refers to the degree to which thesignal that is input to the input terminal 110 is transmitted to theoutput terminal 111, and indicates that the transmission characteristicimproves as the value on the vertical axis of the graph in FIG. 8approaches 0 db.

The signal reflectance S11 refers to the degree to which the signal thatis input to the input terminal 110 is reflected and appears at the inputterminal 110, and indicates that the transmission characteristicimproves as the value on the vertical axis in FIG. 8 decreases.

As can be seen from FIG. 8, the signal transmission rate S21 becomesgreater than the signal reflectance S11 in the frequency band around 9.5GHz. That is, the electromagnetic resonance coupler 10 can transmithigh-frequency signals in the 9.5-GHz frequency band with the frequencyof 9.5 GHz as the center from the input terminal 110 to output terminal111. Specifically, high-frequency signals are transmitted in the 9.5-GHzfrequency band with insertion losses of approximately 0.7 dB.

The operating frequency of the open-ring electromagnetic resonancecoupler having a diameter of 1 mm in FIG. 1 is approximately 15 GHz.Accordingly, the operating frequency of the electromagnetic resonancecoupler 10 according to Embodiment 1 is less than or equal to two-thirdsthat of the conventional electromagnetic resonance coupler. That is, ifthe electromagnetic resonance coupler 10 according to Embodiment 1 isdesigned to transmit high-frequency signals in the 15-GHz frequencyband, the area occupied by the transmission resonator 105 has dimensionsof 0.7 mm by 0.7 mm, which is approximately a half that of theconventional transmission resonator. Accordingly, the size of theapparatus (electromagnetic resonance coupler) can be considerablyreduced.

(Variations)

The electromagnetic resonance coupler 10 using the transmissionresonator 105 (reception resonator 108) that has two recessed portionswas described in Embodiment 1. It is, however, noted that the operatingfrequency and size of the apparatus can be further reduced by providingthree or more recessed portions on the resonators.

FIG. 9 illustrates a variation on the transmission resonator.

A transmission resonator 505 includes six recessed portions thatcorrespond to the second wiring 1052 formed in the internal space 1053illustrated in FIG. 6. Portions surrounded by dotted lines in FIG. 9correspond to the recessed portions.

Because more wirings are close to the periphery of a transmissionresonator slit 506, the electromagnetic field in the periphery of thetransmission resonator slit 506 is further intensified, and thecapacitance component of the transmission resonator 505 is reduced morethan that of the transmission resonator 105. In addition, the inductancecomponent of the transmission resonator 505 is increased more than thatof the transmission resonator 105 because more wirings of thetransmission resonator 505 are close to each other. Accordingly, theelectromagnetic resonance coupler using the transmission resonator 505and a reception resonator each having a shape as illustrated in FIG. 9can further reduce its operating frequency and size.

Note that the transmission resonator slit does not necessarily have tobe provided in a recessed portion. Also, the contour of the transmissionresonator excluding the wiring constituting the recessed portions doesnot necessarily have to the same aspect ratio. In other words, W1′=L1′does not necessarily have to be satisfied in FIGS. 5 and 9.

Note that a transmission wiring 504 and an input terminal 510respectively have the same configurations and functions as thetransmission wiring 104 and the input terminal 110 illustrated in FIG.5.

FIG. 10 illustrates another variation on the transmission resonator.

Because more wirings are close to each other, the transmission resonatorillustrated in FIG. 10 also has a greater inductance component than thetransmission resonator 105. Accordingly, the electromagnetic resonancecoupler using the transmission resonator and a reception resonator eachhaving a shape as illustrated in FIG. 10 can also reduce its operatingfrequency and size.

The above has been a description of the electromagnetic resonancecoupler 10 and variations thereon according to Embodiment 1.

The electromagnetic resonance coupler 10 according to Embodiment 1 caneasily reduce its size and operating frequency by changing the wiringpatterns of the transmission resonator and the reception resonator.

Note that the features of the electromagnetic resonance coupler are thathighly efficient non-contact transmission is possible due to the use ofelectromagnetic resonance coupling, and that unwanted radiation isreduced due to the less likelihood of radio wave radiation. It is alsopossible to isolate (insulate) the grounds between the input and outputterminals and transmit a high-frequency signal.

Embodiment 2

Hereinafter, Embodiment 2 of the present invention will be described.

Embodiment 2 differs from Embodiment 1 only in the shapes of thetransmission resonator and the reception resonator. Thus, the detailsdescribed in Embodiment 1 have been omitted.

A feature of an electromagnetic resonance coupler according toEmbodiment 2 is that its transmission and reception resonators have awound shape (spiral shape), unlike in Embodiment 1.

FIG. 11 is an oblique (perspective) view of an electromagnetic resonancecoupler 20 according to Embodiment 2.

A problem with an electromagnetic resonance coupler using spiral-shapedresonators as disclosed in Patent Literature 2 is its relatively lowtransmission characteristic.

On the other hand, the electromagnetic resonance coupler 20 according toEmbodiment 2 having a configuration as will be described below andillustrated in FIG. 11 enables highly efficient signal transmission andcan be reduced in size.

The electromagnetic resonance coupler 20 illustrated in FIG. 11 includesa transmission substrate 601 formed of a dielectric, a receptionsubstrate 602 formed of a dielectric superimposed above the transmissionsubstrate 601, and a cap substrate 603 formed of a dielectricsuperimposed above the reception substrate 602.

On a top face of the transmission substrate 601, transmission wiring604, a transmission resonator 605, and a coplanar ground 613 are formedof metal wiring made of gold. The coplanar ground 613 is provided by apredetermined distance away from the transmission wiring 604 and thetransmission resonator 605 so as to surround the transmission wiring 604and the transmission resonator 605.

On a top face of the reception substrate 602, reception wiring 607 and areception resonator 608 are formed of metal wiring made of gold.

On a top face of the cap substrate 603, a cap ground 614 is formed ofmetal wiring made of gold. The transmission resonator 605 and thereception resonator 608 have the same shape and size. The transmissionresonator 605 and the reception resonator 608 are disposed facing eachother in a direction perpendicular to a main face of the transmissionsubstrate 601 so that they are symmetric with respect to a point ofintersection between a central axis of the shapes of wirings of thetransmission resonator 605 and the reception resonator 608 and anintermediate plane between the transmission resonator 605 and thereception resonator 608. That is, when viewed in the directionperpendicular to the main face of the transmission substrate 601, thetransmission substrate 601 and the reception substrate 602 aresuperimposed on each other so that the shapes of the transmissionresonator 605 and the reception resonator 608 are symmetric with respectto a point. Also, when viewed in the direction perpendicular to the mainface of the transmission substrate 601, the transmission substrate 601and the reception substrate 602 are superimposed on each other so thatthe contours of the transmission resonator 605 and the receptionresonator 608 match.

Note that in Embodiment 2, the contour of the transmission resonator 605indicates a shape defined by the outer contour of wiring that is routedalong the outermost periphery of the transmission resonator 605.

FIG. 12 illustrates a wiring pattern of the transmission substrate 601according to Embodiment 2.

Hereinafter, the reception resonator 608 is assumed to have the samesize and shape as the transmission resonator 605, and therefore adescription thereof has been omitted.

As illustrated in FIG. 12, in the electromagnetic resonance coupler 20of Embodiment 2, the transmission wiring 604 is connected to a firstconnection portion on the transmission resonator 605. The transmissionresonator 605 is configured by transmission resonator inner wiring 621and transmission resonator outer wiring 620, both branching off from thetransmission wiring 604. Here, the transmission resonator inner wiring621 is wiring that extends from an inner end of the transmissionresonator 605 to the first connection portion. The transmissionresonator outer wiring 620 is wiring that extends from the outer end ofthe transmission resonator 605 to the first connection portion. Notethat a contour 625 of the transmission resonator 605 is square(rectangular) as indicated by the dotted line in FIG. 12. Here, thetransmission resonator inner wiring 621 has a shape of the angled letter“U” (bracket shape).

Note that the transmission resonator outer wiring 620 has a shape thatincludes three bent portions, and the transmission resonator innerwiring 621 has a shape that includes two bent portions. That is, thetransmission resonator 605 has a shape that includes five or more bentportions. The bent portions in this case refer to right-angled portionson the transmission resonator 605.

As in Embodiment 1, the transmission resonator 605 and the receptionresonator 608 make electromagnetic resonance coupling, and ahigh-frequency signal that is input to the transmission resonator 605 istransmitted to the reception resonator 608. The frequency of thishigh-frequency signal is called an “operating frequency” or “resonantfrequency.” A wiring end of the transmission wiring 604 that is notconnected to the transmission resonator 605 forms an input terminal 610of the electromagnetic resonance coupler 20, and a wiring end of thereception wiring 607 that is not connected to the reception resonator608 forms an output terminal 611 of the electromagnetic resonancecoupler 20. That is, a high-frequency signal that is input from theinput terminal 610 is output from the output terminal 611.

A feature of the electromagnetic resonance coupler 20 of the Embodiment2 is that in the transmission resonator 605, the wiring length of thetransmission resonator outer wiring 620 is longer than that of thetransmission resonator inner wiring 621. Another feature is that thewiring length of the transmission resonator outer wiring 620 is longerthan one half a wiring length 624 (length indicated by the dotted linearrow in FIG. 12) of wiring that is routed along the outermost peripheryof the transmission resonator 605.

FIG. 13 shows an insertion loss with the electromagnetic resonancecoupler 20 according to Embodiment 2, when the wiring lengthcorresponding to L2 in FIG. 12 has been changed. Here, the insertionloss refers to an insertion loss at a frequency that gives the minimumloss.

As illustrated in FIG. 13, the insertion loss with the electromagneticresonance coupler 20 decreases as the wiring length corresponding to L2in FIG. 12 increases in the transmission resonator 605. In thespiral-shaped resonator as disclosed in Patent Literature 2, it isconceivable that the insertion loss is considerably large and thusefficient signal transmission is difficult due to the short transmissionresonator outer wiring 620 relative to the transmission resonator innerwiring 621.

The electromagnetic resonance coupler 20 can reduce its operatingfrequency and enables highly efficient signal transmission by increasingthe wiring length of the transmission resonator outer wiring 620.

(Characteristic)

Next is a description of the signal transmission characteristic of theelectromagnetic resonance coupler 20 according to Embodiment 2illustrated in FIG. 11.

First, a specific structure (size) of the electromagnetic resonancecoupler 20 will be described with reference to FIG. 12.

The transmission substrate 601, the reception substrate 602, and the capsubstrate 603 are sapphire substrates having a thickness of 200 μm.

The transmission wiring 604, the transmission resonator 605, thereception wiring 607, and the reception resonator 608 have a wiringwidth of 100 μm, and the transmission resonator 605 and the receptionresonator 608 are each disposed in a square area having dimensions of 1mm by 1 mm (W2=L2=1 mm).

A densely packed wiring lateral distance g1 is 100 μm, and a denselypacked wiring longitudinal distance g2 is 50 μm. The coplanar ground 613is disposed 140 μm (corresponding to g3 in FIG. 12) away from thetransmission resonator 605 and the transmission wiring 604.

FIG. 14 shows the transmission characteristic of the electromagneticresonance coupler 20.

Here, S21 denotes a signal transmission rate at which a signal istransmitted from the input terminal 610 to the output terminal 611, andS11 denotes signal reflectance at the input terminal 610.

As can be seen from FIG. 14, the electromagnetic resonance coupler 20can highly efficiently transmit high-frequency signals in the 9.0-GHzfrequency band with 9.0 GHz as the center from the input terminal 610 tothe output terminal 611. Specifically, the insertion loss in the 9.0-GHzfrequency band is on the order of 0.7 dB. In the case of a conventionalopen-ring electromagnetic resonance coupler that occupies substantiallythe same space and has a diameter of 1 mm in FIG. 1, the operatingfrequency is in the 15-GHz frequency band. That is, the operatingfrequency of the electromagnetic resonance coupler 20 of Embodiment 2 isless than or equal to two-thirds that of the conventionalelectromagnetic resonance coupler that occupies substantially the samespace. Thus, if the electromagnetic resonance coupler of Embodiment 2 isdesigned to transmit high-frequency signals in the 15-GHz frequencyband, the area occupied by the transmission resonator 105 has dimensionsof 0.7 mm by 0.7 mm, which is approximately one half that occupied bythe conventional transmission resonator. Accordingly, it is possible toconsiderably reduce the size of the apparatus (electromagnetic resonancecoupler).

Furthermore, as described in Embodiment 1, the operating frequency canbe further reduced by bringing wirings in the transmission resonator 605close to each other and thereby increasing the inductance component ofthe transmission resonator 505. Specifically, the densely packed wiringlateral distance g1 and the densely packed wiring longitudinal distanceg2 are set to be less than or equal to four times the wiring width ofthe transmission resonator 605. That is, the transmission resonatorinner wiring may include a portion that is close to the transmissionresonator outer wiring at a distance that is less than or equal to fourtimes a predetermined wiring width.

Note that the shape of the transmission resonator according toEmbodiment 2 is not limited to the shape illustrated in FIGS. 11 and 12.

In FIGS. 11 and 12, the transmission resonator inner wiring and thereception resonator inner wiring have a bracket shape. Alternatively,the shapes of the transmission resonator inner wiring and the receptionresonator inner wiring may, for example, be a square or spiral shape asillustrated in FIGS. 15A, 15B, and 15C.

Moreover, as in a transmission resonator 705 illustrated in FIG. 16, thetransmission wiring may be connected to a bent portion on thetransmission resonator. That is, the first connection portion on thetransmission resonator may be provided in a bent portion. In thetransmission resonator 705, transmission resonator outer wiring 720includes two bent portions, and transmission resonator inner wiring 721includes one bent portion. In this case as well, in the transmissionresonator 705, the wiring length of the transmission resonator outerwiring 720 is longer than that of the transmission resonator innerwiring 721. Also, the wiring length of the transmission resonator outerwiring 720 is longer than one half the wiring length of wiring that isrouted along the outermost periphery of the transmission resonator 705.

The above has been a description of the electromagnetic resonancecoupler 20 and variations thereon according to Embodiment 2.

Like the electromagnetic resonance coupler 10 according to Embodiment 1,the electromagnetic resonance coupler 20 according to Embodiment 2 caneasily reduce its size and operating frequency by changing the wiringpatterns of the transmission resonator and the reception resonator.

(Supplement)

Hereinafter, supplementary descriptions are given regarding Embodiments1 and 2.

While the first wiring 1051 and the second wiring 1052 illustrated inFIGS. 5 and 6 are configured as a combination of linear wires, part orthe entire of the wirings may be configured by curved wires.

The coplanar ground provided to surround the transmission wiring 104(transmission wiring 604) and the transmission resonator 105(transmission resonator 605) illustrated in FIGS. 3 and 11 does notnecessarily have to be provided.

Meanwhile, a coplanar ground may be provided in the periphery of thereception wiring 107 (reception wiring 607) and the reception resonator108 (reception resonator 608) illustrated in FIGS. 3 and 11. In thiscase, the coplanar ground is wiring that represents a referencepotential of a high-frequency signal to be transmitted in the receptionsubstrate 102 (reception substrate 602).

At this time, the coplanar ground in the periphery of the receptionwiring 107 (reception wiring 607) and the cap ground 114 (cap ground614) may be electrically connected to each other through the via hole140 as illustrated in FIG. 4. This improves the efficiency of theelectromagnetic resonance coupler 10 (electromagnetic resonance coupler20) in transmitting high-frequency signals.

The transmission resonator outer wiring 620, the transmission resonatorinner wiring 621, the reception resonator outer wiring 622, and thereception resonator inner wiring 623 in FIG. 11 may be configured byserpentine wiring. Alternatively, part or the entire of the transmissionresonator outer wiring 620, the transmission resonator inner wiring 621,the reception resonator outer wiring 622, and the reception resonatorinner wiring 623 may be configured as curved wiring.

The contour 625 of the transmission resonator 605 in FIG. 11 may be of acircular shape, an ellipsoidal shape, or a polygonal shape. The sameapplies to the contour of the reception resonator 608.

The transmission resonator 105 (transmission resonator 605) and thereception resonator 108 (reception resonator 608) does not necessarilyhave to be directly superimposed on each other. That is, space or afluid such as a resin may be provided between the transmission resonator105 (transmission resonator 605) and the reception resonator 108(reception resonator 608).

While the configuration in which the reception resonator 108 (receptionresonator 608) is formed on reception substrate 102 (reception substrate602) has been described, the reception resonator may be formed on theback face (face on which the gap ground is not formed) of the capsubstrate 103 (cap substrate 603). Alternatively, a configuration ispossible in which the reception resonator 108 (reception resonator 608)is formed on the back face of the reception substrate 102 (receptionsubstrate 602), and the transmission substrate 101 (transmissionsubstrate 601) and the reception substrate 102 (reception substrate 602)are superimposed on each other with space or via a dielectric.

Note that in the electromagnetic resonance coupler 10, the transmissionresonator 105 and the reception resonator 108 may be provided onopposite sides of a single substrate. Specifically, a configuration ispossible in which the transmission resonator 105 and the transmissionwiring 104 are provided on one side of a substrate, and the receptionresonator 108 and the reception wiring 107 are provided on the otherside of the substrate. Similarly, in the electromagnetic resonancecoupler 20, the transmission resonator 605 and the reception resonator608 may be provided on opposite sides of a single substrate.

The cap ground 114 (cap ground 614) or the back face ground 112 (backface ground 612) does not necessarily have to be provided.

The order in which the transmission substrate, the reception substrate,and the cap substrate are superimposed is not limited to the ordersillustrated in FIGS. 3 and 11.

It should be noted that the subject matter disclosed herein is notlimited to the exemplary embodiments and the variations thereondescribed above. Embodiments that are obtained by making various kindsof modifications that would have been conceived by those skilled in theart to the exemplary embodiments or the variations thereon, orembodiments that are constructed by combining constituent elements ofdifferent exemplary embodiments or variations thereon are intended to beembraced in the subject matter disclosed herein within a range that doesnot deviate from the gist thereof.

The herein disclosed subject matter is to be considered descriptive andillustrative only, and the appended Claims are of a scope intended tocover and encompass not only the particular embodiments disclosed, butalso equivalent structures, methods, and/or uses.

INDUSTRIAL APPLICABILITY

The electromagnetic resonance coupler according to one or more exemplaryembodiments disclosed herein can be easily reduced in size and isapplicable as, for example, a small non-contact power transmissionapparatus, an electric signal insulating element, or an insulationsemiconductor driving element.

1-19. (canceled)
 20. An electromagnetic resonance coupler fortransmitting a signal between first resonant wiring and second resonantwiring without contact, the electromagnetic resonance couplercomprising: a first substrate; and a second substrate facing the firstsubstrate, wherein the first resonant wiring and first input/outputwiring are provided on the first substrate, the first resonant wiringhaving a loop shape that includes a first recessed portion and a secondrecessed portion which are inwardly recessed and an opening, and thefirst input/output wiring being connected to the first resonant wiring,the second resonant wiring and second input/output wiring are providedon the second substrate, the second resonant wiring having the samewiring width and the same shape as the first resonant wiring, and thesecond input/output wiring being connected to the second resonantwiring, when viewed in a direction perpendicular to a main face of thefirst substrate, the first resonant wiring and the second resonantwiring are symmetric with respect to a point, and contours of the firstresonant wiring and the second resonant wiring match, a distance betweenthe first resonant wiring and the second resonant wiring in thedirection perpendicular to the main face of the first substrate is lessthan or equal to one half a wavelength of the signal, when viewed in thedirection perpendicular to the main face of the first substrate, thefirst recessed portion and the second recessed portion are facing eachother, when viewed in the direction perpendicular to the main face ofthe first substrate, an area in which an inner end of the first recessedportion and an inner end of the second recessed portion are close toeach other at a distance less than or equal to four times the wiringwidth of the first resonant wiring is provided in the first substrate,and the opening is provided in a portion at which the inner end of thefirst recessed portion is close to the inner end of the second recessedportion at a distance less than or equal to four times the wiring width.